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4 modification, are permitted provided that the following conditions
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15 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
16 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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26 ***********************************************************************/
27
28 #ifdef HAVE_CONFIG_H
29 #include "config.h"
30 #endif
31
32 #include "main_FIX.h"
33 #include "stack_alloc.h"
34 #include "tuning_parameters.h"
35
36 /* Finds LPC vector from correlations, and converts to NLSF */
silk_find_LPC_FIX(silk_encoder_state * psEncC,opus_int16 NLSF_Q15[],const opus_int16 x[],const opus_int32 minInvGain_Q30)37 void silk_find_LPC_FIX(
38 silk_encoder_state *psEncC, /* I/O Encoder state */
39 opus_int16 NLSF_Q15[], /* O NLSFs */
40 const opus_int16 x[], /* I Input signal */
41 const opus_int32 minInvGain_Q30 /* I Inverse of max prediction gain */
42 )
43 {
44 opus_int k, subfr_length;
45 opus_int32 a_Q16[ MAX_LPC_ORDER ];
46 opus_int isInterpLower, shift;
47 opus_int32 res_nrg0, res_nrg1;
48 opus_int rshift0, rshift1;
49
50 /* Used only for LSF interpolation */
51 opus_int32 a_tmp_Q16[ MAX_LPC_ORDER ], res_nrg_interp, res_nrg, res_tmp_nrg;
52 opus_int res_nrg_interp_Q, res_nrg_Q, res_tmp_nrg_Q;
53 opus_int16 a_tmp_Q12[ MAX_LPC_ORDER ];
54 opus_int16 NLSF0_Q15[ MAX_LPC_ORDER ];
55 SAVE_STACK;
56
57 subfr_length = psEncC->subfr_length + psEncC->predictLPCOrder;
58
59 /* Default: no interpolation */
60 psEncC->indices.NLSFInterpCoef_Q2 = 4;
61
62 /* Burg AR analysis for the full frame */
63 silk_burg_modified( &res_nrg, &res_nrg_Q, a_Q16, x, minInvGain_Q30, subfr_length, psEncC->nb_subfr, psEncC->predictLPCOrder, psEncC->arch );
64
65 if( psEncC->useInterpolatedNLSFs && !psEncC->first_frame_after_reset && psEncC->nb_subfr == MAX_NB_SUBFR ) {
66 VARDECL( opus_int16, LPC_res );
67
68 /* Optimal solution for last 10 ms */
69 silk_burg_modified( &res_tmp_nrg, &res_tmp_nrg_Q, a_tmp_Q16, x + 2 * subfr_length, minInvGain_Q30, subfr_length, 2, psEncC->predictLPCOrder, psEncC->arch );
70
71 /* subtract residual energy here, as that's easier than adding it to the */
72 /* residual energy of the first 10 ms in each iteration of the search below */
73 shift = res_tmp_nrg_Q - res_nrg_Q;
74 if( shift >= 0 ) {
75 if( shift < 32 ) {
76 res_nrg = res_nrg - silk_RSHIFT( res_tmp_nrg, shift );
77 }
78 } else {
79 silk_assert( shift > -32 );
80 res_nrg = silk_RSHIFT( res_nrg, -shift ) - res_tmp_nrg;
81 res_nrg_Q = res_tmp_nrg_Q;
82 }
83
84 /* Convert to NLSFs */
85 silk_A2NLSF( NLSF_Q15, a_tmp_Q16, psEncC->predictLPCOrder );
86
87 ALLOC( LPC_res, 2 * subfr_length, opus_int16 );
88
89 /* Search over interpolation indices to find the one with lowest residual energy */
90 for( k = 3; k >= 0; k-- ) {
91 /* Interpolate NLSFs for first half */
92 silk_interpolate( NLSF0_Q15, psEncC->prev_NLSFq_Q15, NLSF_Q15, k, psEncC->predictLPCOrder );
93
94 /* Convert to LPC for residual energy evaluation */
95 silk_NLSF2A( a_tmp_Q12, NLSF0_Q15, psEncC->predictLPCOrder );
96
97 /* Calculate residual energy with NLSF interpolation */
98 silk_LPC_analysis_filter( LPC_res, x, a_tmp_Q12, 2 * subfr_length, psEncC->predictLPCOrder, psEncC->arch );
99
100 silk_sum_sqr_shift( &res_nrg0, &rshift0, LPC_res + psEncC->predictLPCOrder, subfr_length - psEncC->predictLPCOrder );
101 silk_sum_sqr_shift( &res_nrg1, &rshift1, LPC_res + psEncC->predictLPCOrder + subfr_length, subfr_length - psEncC->predictLPCOrder );
102
103 /* Add subframe energies from first half frame */
104 shift = rshift0 - rshift1;
105 if( shift >= 0 ) {
106 res_nrg1 = silk_RSHIFT( res_nrg1, shift );
107 res_nrg_interp_Q = -rshift0;
108 } else {
109 res_nrg0 = silk_RSHIFT( res_nrg0, -shift );
110 res_nrg_interp_Q = -rshift1;
111 }
112 res_nrg_interp = silk_ADD32( res_nrg0, res_nrg1 );
113
114 /* Compare with first half energy without NLSF interpolation, or best interpolated value so far */
115 shift = res_nrg_interp_Q - res_nrg_Q;
116 if( shift >= 0 ) {
117 if( silk_RSHIFT( res_nrg_interp, shift ) < res_nrg ) {
118 isInterpLower = silk_TRUE;
119 } else {
120 isInterpLower = silk_FALSE;
121 }
122 } else {
123 if( -shift < 32 ) {
124 if( res_nrg_interp < silk_RSHIFT( res_nrg, -shift ) ) {
125 isInterpLower = silk_TRUE;
126 } else {
127 isInterpLower = silk_FALSE;
128 }
129 } else {
130 isInterpLower = silk_FALSE;
131 }
132 }
133
134 /* Determine whether current interpolated NLSFs are best so far */
135 if( isInterpLower == silk_TRUE ) {
136 /* Interpolation has lower residual energy */
137 res_nrg = res_nrg_interp;
138 res_nrg_Q = res_nrg_interp_Q;
139 psEncC->indices.NLSFInterpCoef_Q2 = (opus_int8)k;
140 }
141 }
142 }
143
144 if( psEncC->indices.NLSFInterpCoef_Q2 == 4 ) {
145 /* NLSF interpolation is currently inactive, calculate NLSFs from full frame AR coefficients */
146 silk_A2NLSF( NLSF_Q15, a_Q16, psEncC->predictLPCOrder );
147 }
148
149 silk_assert( psEncC->indices.NLSFInterpCoef_Q2 == 4 || ( psEncC->useInterpolatedNLSFs && !psEncC->first_frame_after_reset && psEncC->nb_subfr == MAX_NB_SUBFR ) );
150 RESTORE_STACK;
151 }
152